Means



6 16,667 July 7' E. HEWLETT ET AL Re MEANS FOR REPRODUCING POSITION Original Filed Aug. 2. 1923 Inventor: Edward MHewlett, \X/aldo \X/.\X/Lllar d TheLPAttoP Rams- July 1927.,

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MEANS I'OiBi REPBODUOING POSITION.

Original 1m.- 1,s4':,aea, dated Iu1y128, 1925, Serial in. 655,359, filed August 2, 192a. reinue filed Iay 10, 1827. Serial No. 190,355;

This invention relates to means for repro- "ducing position, and has for its object the provision of. simple, reliable and eflicientmeansfor maintaining an object in posi- 6 tion'al agreement with a controlling object.

More specifically our invention relates to sistems for reproducing position in which t e motion of-a controlling object is utilized through suitable mechanism to control a 10 remote servo motor so asto cause the servo motor to drivea second or controlled'object into positional agreement with the first.

In carrying out our invention in one form,

we rovide means for producing an electro- 5 motiveforce which is substantially proportional in amount and direction to-any positional disagreement between the two ob ects,

together with means responsive to this elec'- tromotive force for controlling the driving motor for the driven object.

For a better understandin of our invention reference should be ha to the accompan'ying drawing, Fig. 1 of which shows in diagrammatic form means for reproducing position embodying our invention, while Figs. 2 and '3 are modified forms of our invention.

i Referring to the drawing, we have shown" our invention in one form as applied to the automatic controlling of the position of a.

remote searchlight 10 so as to maintain the Searchlight in a predetermined angular relation with acontrolling ob'ect which .is

shown as a telescope 11. It is desired, for

example, to automatically move the searchli ht so that it is directed on the object at which the telescope is pointed. Operatively connected to the telescope 11' is an inductive device 12 comprising in the form shown a field winding 13 rotatably mounted and driven by movement of the telescope in a horizontal lane or in azimuth; anda stationary po ycircuit armature windin 14 shown as a three-phase distributed win ing. Thefield winding 13- is energized from a suitable source of' alternating current 15. Operatively connectedto the searchlight 10 .in such manner as to be responsive to its movement in azimuth is a second inductive device 16 similar in construction to the de-' vice 12; This second inductive device -comprises a three-phase armature winding 17 and a winding 18 which is rotatably mounted and has its shaft 18" operatively connected through suitable gearing 19 to the Searchlight 10 so asto be moved in response to movement of the Searchlight in azimuth.

7 The windings 13 and 18 are preferably conwhich has a valuedependent on the angular.

disagreement in azimuth of the telescope and searchlight and which has a direction with respect to the alternating current sup ply source 15 determined by the direction of thisdisa reement. The devices are connected to t e telescope and searchlight in suchmanner that when the Searchlight is in angular agreement with the telescope, as shown in the drawing, the winding 18 is in a position with relation to armature winding 17 which is at ri ht angles to the position of 'the field wind armature. winding 14. In this position of winding 18, it is at right angles to :the field generated by armature winding 17 due to energy su plied to it from inductive. device 12. It w 1 be observed that field winding 13 induces a set of voltages in the various circuits of its cooperating armature winding 14, which set of voltages are impressed on armature winding 17 whereby a field is set up by winding 17 having a direction corresponding to the direction of the field set up by field winding '13 so that it does not cut winding 18 when in the position shown and henceno voltage is induced therein. In case of angular disa eement of winding 18 with respect to win ing 13 it will be observed that a voltage will be induced in winding 18 which voltage will be substantially ropertional in value to the amount of angu ar disagreement and will have a direction with resgect to alterating current supply source 15 etermined by the direction of the angular disagreement.

It will be understood that any rotation Application for ing 13 with relation to I of the field winding 13, due to movement of the telescope in azimuth roduces a corresponding rotation ofthe fie d produced by the armature winding 17. In other vwords, the field of winding 17 is-caused to rotate in accordance with the movements of the telescope, and upon such rotation of this field relative to windin '18 the aforesaid voltage is induced in t 'e winding 18 by reason of the fact that the field is an alternating one.

The Searchlight is driven in azimuth by an electric driving motor 20 of a direct current type which motor is controlled in response to the volta e induced in winding 18 so as to maintain the Searchlight. in angular agreement with the telescope. The motor 20 is shown as provided with two armatures 21 and 22 on a common drivin shaft 23, the

armatures being rovided with 'field'windings 24 and 25. he field windings are 'connected in series to a source of direct current supply 20. .As shown, shaft 23 is a continuation of shaft 18 and is connected through gearing 19 tothe Searchlight.

For the control of the motor 20 the else tromotive force induced in winding 18 upon angular disagreement of the telescope and the Searchlight is impressed on the input'or grid circuits of two electron. discharge am.- pliiym devices or'tubes 26 and 27, shown as of t e three electrode type. This connection is preferably efiected through a transformer 28, the secondary 29 of whichv 1 1s provided with a central tap so that one half 30 of the secondary is connected in the 2 input or other halt 31 is connected in the in ut cir-- ridcircuit of tube 26, while the cuit of tube 27. The .output or p ate circuits of the'tubes. are connected to the two halves 32 and 33 of the primary of a transformer 34 having a secondary winding 35.

' The two tubes 26 and 27 are thus connected qu1red to control the grids of the 'tubes is applied to the winding 18.

This amplified output of impressed in turn on the id or input circuits of two electron disc arge devices or tubes 36 and 37, also shown of the three electrode type, the entire voltage of the sec 1m-- pressed on the grids of both tubes. Theondary of the transformer 34 being plate circuits of the tubes 36 and 37 d are energized from the alternating current sup-'" ply source 15 through suitable transformers 38 and 39, the connections of the transformers bein such that their voltages are opposite n irection so that at any given winding 13 is 7 race? 1 instant the plates of the tubes 36 and 37 have opposite polarities. The armature 21 is connected in the plate circuit of tube 36 when transformer 34 impresses a voltage on the grids of tubes 36 and 37 due to movement of the telescope, one or the other of the armatures 21 or 22 will be energized depending on the polarity of the output of transformer 34. For example, if' the polaritfy of transformer 34 is such that the grid 0 tube 36 is positive at the same instant that its plate is positive, then a current will flow through armature 21, causing motor 20 to operate in one direction, whereb the searchlight will be driven to follow t e telescope. Whc'n the searchli 'ht reaches angular agreement with the to escope resulting in zero voltage across the terminals of winding 18, and hence zero'voltage impressed by transformer 34, no current will flow in armature 21'and the motor will come to rest. Upon movement of the telescopein the opposite is to ow in armature 22 and the motor 20 0 erated in the opposite direction until t e Searchlight is again brought into angular agreement with the telescope.

To improve the operation, condensers 40 :37 wherebywthe grid of tube 37 will- 05 i fiositive, so that a current will be caused f I and 41 are connected across the two halves inductance of the armature circuits." This increased inductance of the armature circuits tends to flatten out the pulsating currents supplied thereto from the electron tubes, thereby improving the operation of the motor. A condenser 44 is connected across armature 21 and coil 42, whilea con-. denser 45 is similarly connected across arma ture 22 and coil 43. ,The function ofthese condensers is to absorb voltage surges due tothe inductance of the armature circuits..

i In the modified formof our invention.

showirinFig. 2, the armatures are connected vacuum tubes. Obvious] 'a motor' having a sin le armature and di erential field'coilsf v I. used. Condensers 46 and 47. are con may nected across the field coils respectivel "to absorb voltage surges due to .the so] in? .ductance of the field coils, thus preventing arcing. and smoothing out the current flowj 3o in t e field circuits.

12o in series across the supply source, while the. fieldcoils 24 and 25'are energized from the As shown in Fig. 3, for the purpose of further amplification, the electron tubes may be'connectd toselectively energize differential field coils 48 and 49 of an electric generator 50, which in turn 'sup lies amplified power to the armature 51 o the electric. driving motor 52 for the Searchlight. The field coil 53 of the motoris connected across a suitable supply source 54. Obviously if-further amplification is desired, a plurality of generators may be used connected so that the armature of one energizes the field of the next.

While we have described our invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that we do not limit our invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of our invention, the scope of which is set forth in the annexed claims' tor whereby said motor is caused to drive said driven object into positional agreementwith said controlling object.

2. Means for reproducing position comprising in combination with, acontrolling ance with the movements of sai object and a driven object, driving means for said driven object, means for producing an alternating electromotive force upon angular disagreement of said objects having a direction determined by the direction of such angular disagreement, and ower amplifying means responsive to SEIdYBIBCtIO-fl .motlve force arranged to selectively apply its amplified output to control said motor in accordance with the direction of said electromotive force, whereby said motor is caused to drive sai'd driven object into positional agreement with said controlling obect. a v I a 3. Means for reproducingi prising in combination wit 'a controlling object and a driven object remote from said' controlling object, a driving motor for said driven ob ect, means for producing an ,al-

in accordcontrollin Object, a coil inductively associated with said field in which an electromotive force is induced by said field, control means responsive ternating magnetic field rotatin position com motor upon angular movement of sai controlling object, and means for changin the angular relation of said field and Sahf coil in accordance with the movements ofsaid' ing connection between said controlling ob-- ject and'said rotatable winding, a source of to said electromotiveforce forstartin said I alternating current supply for said field winding, 8. secondinductlve device provided with similar windings, a driving connection between said driven object and the rotatable winding of said second device, electrical con'-- said devices whereby an electromotive force is induced 1n the field wlndmg of said second device upon angular disagreement of said nections between the armature windings of v objects, a'motor for driving said d-riven'ob-' jec t, and control means'for said motor res onsive to said electromotive force to cause t e motor to drive saiddrivenobject into positionalagreement with saidcontrolling object.

5. Means for rep-roducin position comelectromotive force to cause-the motor to drive the driven object into positional agreement with the controlling object,

6. Means for reproducing position "com-l a controlling prising in combination .with' a controlling object and a driven object, a driving motor for said driven ob'ect, means for producing an electronioti've orce upon positlonaldis agreement of said objects corresponding value and direction to the amount and direction of such positional disagreement, and means comprising electron discharge dev ces responsive to said electromotive force for cont-rollingvsaid motor to drive said driven" object into prising in combination with a controlling object and a driven object, a. driving motor for said driven obect, means for producing 'an' electromotive orce upon positional disagreement of said objects corresponding in value and direction to the amount and di-' rection of said positional disagreement, and

' electron discharge devices controlled by said electromotive force and connected tocontrol the energization of said motor. so as to cause 'said motor to drive the driven object into positional agreement with the controlling object.-- I v 8. Means for reproducing position'comprising in combination with a controlling object and a driven object, an electric driv ing motor for said driven object, inductive means for producing an electromotlve force 7 upon positional disagreement of said chin value and direction jects correspondin direction of said posito the amount an I tional disagreement, and a pluralitg'yof elecdriven ob tron discharge devices for .ampli ing the output ofsaid inductive means and connected to control the energization of said motor so as to cause said motor to drive the cot into-positional agreement with p the controlling object.

9. Means for reproducing position comprising in combination with acontrolling object and a driven object, driving means for said driven object, two electron discharge amplifying devices for controlling said drivmg means, a source of alternating current :"i ri'sing in combination Wi bject and a driven- Obj n electric dnv" I trollin objec supply connected to energize the plate output-circuits of said devices in opposite direc tions, and means for impressing a voltage on the input circuits of said devices having a direction corresponding to thepolarity of one or the other of the plates of said devices depending on the direction of the angulardisagreement between said objects, whereby ener is supplied by one or the other of said evicesto cause the driven object to-be drivenintoangular agreement with the con-c 10. cans for reproducingposition coming motor for said-. 'driven object, inductive meansfor producing an electromotive force upon positional disagreement of said object's corresponding in value and direction to the amount and directionof said positional disagreement, a source ohalternatmg current I supply ior'said inductive means, anda plu- 0f electron discharge amplifying de-.

vices having their input circuits energized f by said inductive means and their output cirsaid supp y source and connected to control cuitsenerlgimed in opposite directionsfrom said motor, whereby energy is supplied from 'one=.-{or the other of said devices depending on the direction of the angular disagreement between said objects to cause said motor to object into 'ducing an electromotive a controlling drive the driven object into angular agreement with the controlling object.

11.- Means for reproducin position comprising in combination with a controlling object and a driven object, an electric driving motor for said driven object, aninductive device connected to said controlling object having a polycircuit armature winding and a cooperating field winding, a source of alternating current supply for said field winding, an inductive device having similar driven object, electrical connections between the armature windings of said devices whereby an electromagnetic field isin'oduccd bythe armature winding of said second device having a definite angular relation to the angular-position otsaid controlling object an inducing an electromotive force in the field winding of 581d second device corresponding in value and direction to the amount and direction of the angular disy agreement betweensa'id objccts,tan.d vw plu rality of electron discharge devices having their inputcircuits controlled in response to said electromotive force and theiroutput circuits connected to-control said motor, and

electrical connections between the output cir cuits of said devices and said alternating current supply source such that voltages of ,windings operativcly connected tov said opposite direction are im ressed on said out- But circuits, whereby sai motoris controlled y one device to drive said driven object in one direction and by another device to drive the driven ob'ect in a reverse direction in accordance wit the direction of the electromotive force impressed on the input ci'rcuits of said devices'so' as-to drive said driven controlling vo ect.-

rositional agreement with said 12. Means or reproducin position comprising in combination wit 1' a controlling object and a drivenobjeci; means for protional disagreement of said ob'ects' corresponding m value and direction to Y the amount and direction of such positional disagreement, a plurality of electron discharge orce upon. posidevices having their input 'circuitsfenergized by said electromotive' force, a driving motor for said driven object,- an' electric generator for supplying rality of fiel windings for said generator, and electrical connections between said fields and the output circuits of said electron discharge devices. a

'13. Means for reproducing position comprising in combination with a controlling;

object and a driven object, inductive means for producing an .electromotive force upon positional disagreement of-said objects corresponding in' value and direction to the amount and direction of such positional disagreement, a source-of alternating current supply for said inductive means, two elecnet.

energy to said motor, a plutron discharge devices havin their input circuits energized by said in uctivemeans and their output circuits energized in opposite directionsrom said supply source, a 5 driving motor for said controlled object, an electric generator for su 1 ng energy to said motor, a plurality o ei d windings for said generator, and electrical connections between said' field windings and the output circuits of said electron discharge devices.

In witness whereof; we have hereunto set our handsthis 9th day of May 1927.

' EDWARD M. HEWLETT.

WALDO w. WILLARD. 

